U.S. Pat. No. 3,880,593 to Windal describes a crystallization apparatus in the form of a cylindrical tank with a floating calandria or a fixed calandria. A lower portion of the tank has radially extending dividing walls to define therebetween a plurality of compartments located in series with one another. The dividing walls have ports at their bases to permit the continuous flow of a solute containing solution from one compartment to the other. The bottom of the tank has an inverted V-shape. Feeding means for feeding an undersaturated solution of the solute into successive compartments is arranged in an upper portion of the tank for rotation about the vertical axis of the tank to sweep over successive compartments. Shutters are provided for controlling the amount of the undersaturated solution fed to each of the compartments.
South African patent 84/6920 to the applicant describes a continuous vacuum pan crystallizer which is essentially a long path horizontal vessel with vertical tube floating calandrias in each compartment.
It is an object of this invention to provide an improved continuous vacuum pan.